\$\begingroup\$The page you are quoting is from a D&D 3.5e wiki, and likely not very relevant to D&D 5e at all.\$\endgroup\$
– doppelgreener♦Apr 5 '15 at 9:10

\$\begingroup\$@doppelgreener I was not sure which edition the wiki page was for. My hope was with 5e baseline fall damage being a D6 that it was my most likely starting point for a house-rule. It is pretty much the only thing i have found that broke down objects like that.\$\endgroup\$
– QuiescatApr 5 '15 at 15:53

4 Answers
4

Think of falling objects as traps and use the damage severity levels in the DMG as guidance

Using the same rules for falling damage and damage from a falling object breaks down when you start to consider different types of objects. A vase knocked down from a shelf and hitting a character is likely to destroy the vase but, depending what the vase is made of, only slightly set back the character. From the same height a dropped stone statue may knock a character unconscious.

Luckily the DMG gives some guidance on this. DMG p.121 introduces the idea of setting trap damage by combining character level and the severity of the trap. This is a very useful concept as it makes it easy to go from a thematic description (An armored bear falling from the roof) to the rules effect (A deadly trap but perhaps easily dodged).

Lastly DMG p.122 provides an example, "collapsing roof", trap that I think is valuable to consider. The damage from the roof is 4d10, a dangerous trap, however to end up taking that damage a character would have to first miss an easy check to spot the trip wire and a moderate check to take half damage. Handling falling objects as traps to be avoided rather than attacks being made helps to keep falling objects from becoming too powerful as well as encouraging players to think about them as something special.

I've actually built a chart for this a while ago. I based it on science.

I used weight, height and gravity, and calculated the energy output. I based that on the enegery of a punch (IRL) vs unarmed strike damage (in game). I didn't factor in air resistance to keep it simple and used the d6 to make up for that variable anyway.

I ended up with something like this. Double the height = double the damage (or dice rolled)

Interestingly enough the lower damage was the most unrealstic because the numbers can be pretty small. Enough height though and you can get a 1 pound item traveling fast enough to kill.

The system has played out great. I built this specifically for an area that was just constantly falling objects due to wormholes and such.

The numbers work because the dice give it variable damage and everything was calculated around averages. So it derived from science, but it isn't hard science. The rolls give pretty big ranges the higher you go, leaving plenty of room for fudging, modifiers, and saves if needed. Plus people love that they can roll tons of dice.

One last thing to note, is the reason this table was made in the first place, was to account for weight which was important in the setting. There are other methods that might even already exist, like using traps or falling damage, but they don't really account for weight. Which is odd because a tiny thing falling and a huge thing falling will have VASLTY different end results. One walking away, the other exploding into goop.

I could alway post a link to the google sheet with all the calculations too if needed.

You'll also note that giants, which are all Huge creatures, deal the same base damage with a rock sized for a Huge creature- 4d10. Treants, also Huge creatures, use the same base damage for a rock. This would indicate the damage dealt by the rock's weight itself is 4d10 damage (the varied Strength bonuses accounts for the force used to hurl the rock). Last, there is certainly no rule that states that any weapon, improvised or otherwise, deals damage based on how far it falls first. That would include a body... like, say, a bear. We can thus conclude that it is the size of the object falling that is the determining factor. This is confirmed by the collapsing roof trap- the amount of damage given is not dependent on how far the roof falls before hitting the character, but how much of it will (with the assumption being roughly a 5'x5' section of roof).

If we're treating falling objects as weapons, scaling damage becomes pretty straightforward. The standard rule is that a weapon gains a die of damage with every size category increase, and likewise loses a die of damage for each size category it drops by. At this point a little guesswork is necessary, as it is never explicitly stated what size category those rocks hurled by Huge creatures is in, but given the assumptions made so far and previous editions, a safe bet would be Medium.

Is this table perfect? No. Per this table, rocks dropped by Medium and smaller creatures should be in the range of 11 (2d10) damage, and instead we see about 6 for the winged kobold. If we call for a Dexterity saving throw for half damage, however, the damage output falls nicely in line. Using the collapsing roof as our basis, the DC for a falling object powered by gravity would be 15.

In my home campaign I'm slightly lazier than than this, opting for a 2/4/6/8d10 rule — but this is the table I came up with after the first time a character tried to use themselves as a missile weapon. I also have a standing rule that the listed damage only applies if the object/character has fallen at least 100 feet, so that for example the crazy gnome warlock that keeps jumping off his flying horse would deal 4d10 extra damage (lazy table version) if he hits, but take 10d6 damage doing so.

\$\begingroup\$This makes sense for a couple of reasons, but the easiest to see is that it would obviously hurt far more if a bear landed on you than a kobold. You can also arbitrate if you feel it silly that a 30-pound creature landing on your head should potentially kill you... though that is two bowling balls' worth of pain, and IRL even a coconut that hits just right can drop people.\$\endgroup\$
– TheVagrantDogSep 22 '17 at 5:45

1

\$\begingroup\$I feel size alone might be too little; a bear hurts, but a rock of the same size hurts much more, because it would weigh about 10 times as much.\$\endgroup\$
– ErikSep 22 '17 at 5:51

\$\begingroup\$Size can be used in two ways, mind- dimensions and weight. A Large bear, for example, clocks in at 400 pounds- and I'd argue that a rock weighing that much will hurt about as much. A rock and a bear of the same mass will hit you in different ways, yes, but for game purposes and calculating on the fly, saying both will do somewhere between 5 and 50 points of damage is, I feel, close enough.\$\endgroup\$
– TheVagrantDogSep 22 '17 at 5:59

\$\begingroup\$I am torn, though, on whether an object's dimensions should play the more prominent role. Should a marble weighing 400 pounds deal as much damage as 400 pounds of bananas in a sack? And if so, should the size of the target also be taken into account? For now, I'm falling back on the same logic used for advantage and disadvantage- if you have two or more factors tugging in opposite directions, consider them all canceled out.\$\endgroup\$
– TheVagrantDogSep 22 '17 at 6:04

1

\$\begingroup\$One note is that the Hill Giant only does 3d10 damage with a rock (and is a huge creature), suggesting that this damage is scaling with CR instead of creature size.\$\endgroup\$
– BaergrenSep 22 '17 at 16:02